In animation processes, characters can be represented using geometric elements that are caused to undergo the desired motion of the character. A geometric element, such as a limb, has a surface representation that is to be the basis for the image of the character that is later generated in a rendering process. Various processing is performed to generate the surface representation and to subsequently subject it to the character's movement.
Characters in an animated motion picture are sometimes provided with unnatural abilities or features, such as them being impervious to injury or having unlimited strength. Viewers typically accept this as legitimate exercises of artistic freedom, perhaps because it is apparent that it is a direct outflow of the artist's or creator's imagination. In other respects, however, it is desirable or necessary that animated characters behave more naturally. This can include, but is not limited to, the appearance and behavior of the character's body, clothing and other items. That is, if a character has arms and legs viewers will often expect that these should behave more or less as on a real human (or other animal the character is based on). Particularly, it can be important to provide a natural appearance when various parts of the character are in motion and/or change shape due to movement.